Spirostachys africana (PROTA)

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Plant Resources of Tropical Africa
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Spirostachys africana Sond.


Protologue: Linnaea 23: 106 (1850).
Family: Euphorbiaceae

Vernacular names

African sandalwood, Cape sandalwood, headache tree, tamboti (En). Sandalo africano (Po). Msarakana (Sw).

Origin and geographic distribution

Spirostachys africana occurs from south-eastern Kenya south to Namibia, Botswana, Zimbabwe, Mozambique, South Africa and Swaziland.

Uses

The wood is in high demand for decorative joinery, furniture and cabinet work, and for carvings and turnery. It is also appreciated for use in house construction for posts, beams and roof laths, and to make scented beads for necklaces. It is suitable for heavy flooring, mine props, ship building, toys, novelties, agricultural implements and musical instruments. It is also used as fuelwood, but should not be used for cooking because of the toxic smoke; the branches have been used for making scented torches. The wood is not appreciated for charcoal production.

The roots, bark and latex are widely used in traditional medicine. Root decoctions are taken to treat malaria, constipation but also diarrhoea, cough, gonorrhoea and headache, and they are dropped into the eyes to treat ophthalmia. Bark decoctions and infusions in small dosage are used as purgative to treat constipation but also diarrhoea, and to treat stomach ulcers, kidney complaints, cough and eye complaints, and to purify the blood. Dried bark is applied to rashes in children. Powdered bark is taken as anthelmintic. Latex diluted in water is taken as emetic and purgative, and the latex is administered against toothache and as anodyne. It is also applied to sores in cattle to kill maggots, whereas the wood serves as insect repellent. Extreme caution is needed when bark or latex is administered for medicinal purposes. Several complications caused by an overdose and resulting in the death of patients have been recorded. Extracts are used in the treatment of opportunistic oral infections such as candidiasis in HIV-infected patients, and although they have potent antifungal activity, they should be used with care because they may have interactions with antiretroviral agents. The bark has been used as fish poison, and the latex as hunting poison for arrow heads. Leaf decoctions are applied to the eyes to treat ophthalmia. In Namibia the powdered oily wood, mixed with fat, has been rubbed into the hair, and it has also been used as perfume.

Production and international trade

A study in 2003 in Maputo (Mozambique) showed that the wood of Spirostachys africana is commonly used by wood artists. The annual volume was estimated at 360 m³. In general, it has been reported that about 40 m³ of Spirostachys africana wood per month is available from sustainably managed sources.

Properties

The heartwood is brown to dark brown with darker markings and streaks, and distinctly demarcated from the whitish to pale yellow, 2.5–5 cm wide sapwood. The grain is straight to slightly wavy, texture moderately fine to fine, and even. The wood has a beautiful banded figure and a satin-like lustre, with an oily surface. It has a fragrant, spicy smell, resembling that of East Indian sandalwood (Santalum album L.), which can persist for many years.

The wood is very heavy, with a density of 910–1090 kg/m³ at 12% moisture content, and hard. It air dries slowly. Boards of 2.5 cm thick take about 7 months to air dry and boards of 10 cm thick about one year. End checking is common, but the wood is usually not very liable to distortion. The rates of shrinkage are low, from green to oven dry 2.1–3.5% radial and 4.0–6.7% tangential. Once dry, the wood is moderately stable in service.

At 12% moisture content, the modulus of rupture is 102–108 N/mm², modulus of elasticity 8600–9210 N/mm², compression parallel to grain 57–60 N/mm², shear 16 N/mm² and Janka side hardness 8940 N.

The wood is difficult to saw, particularly green wood, but it is more easy to work. It rapidly blunts saw teeth. The saw dust is gummy and sticks to the teeth. The wood near the centre of the log may be extremely hard to saw. It planes smoothly and moulds well. Drilling and mortising require considerable effort, and nailing is only possible after pre-boring. Turning gives excellent results. Sanding is difficult because of the oily wood surface. The wood is durable and resistant to fungi, termites and wood borers. It is very resistant to preservatives. The sawdust is highly irritant to eyes and respiratory tracts. The wood is not well suited as firewood because the smoke is irritant, causing headache and complaints of the respiratory organs.

The latex is irritant and may cause inflammation and blistering of the skin. It is particularly harmful when in contact with the eyes. It may cause severe purging and vomiting. It contains a complex mixture of diterpenes. Bark extracts showed antibacterial activity and genotoxicity in tests. Experiments showed that powdered bark suppressed populations of the cowpea weevil (Callosobruchus maculatus) in stored cowpea seeds. The bark contains diterpenoids, triterpenoids, tannins, anthocyanins and saponins. Several diterpenoids have been isolated from the heartwood.

Description

Deciduous, dioecious or monoecious shrub or small tree up to 15(–20) m tall, with white latex; bole branchless for up to 7 m, straight or bent, up to 50(–90) cm in diameter, more or less fluted near base; bark surface rough and flaking in rectangular scales, dark grey to dark brown or black, inner bark fibrous, dark red, exuding white latex; crown rounded, heavily branched; twigs glabrous, with lenticels. Leaves arranged spirally, simple; stipules triangular-ovate, c. 1 mm long, caducous; petiole 0.5–1(–1.5) cm long, channelled above, with 2 small glands at apex; blade ovate to elliptical, (1.5–)2–7 cm × (0.5–)1–3.5 cm, usually rounded at base, obtuse to rounded or slightly short-acuminate at apex, margins obtusely toothed, papery to thinly leathery, glabrous, pinnately veined with 6–14 pairs of lateral veins. Inflorescence an axillary spike 1–2.5 cm long, densely flowered, with only male flowers or with many male flowers and 1–3 female flowers at base; bracts arranged spirally, broadly ovate, c. 1.5 mm broad. Flowers unisexual, regular, sessile or nearly so; petals and disk absent; male flowers with (2–)3 obovate to rounded sepals c. 1 mm long, stamens 3, fused at base into a tube; female flowers with 5 triangular-ovate sepals c. 1 mm long, ovary superior, c. 1 mm in diameter, 3-lobed and 3-celled, styles 3, c. 1.5 mm long, fused at base, with red stigmas. Fruit a 3-lobed capsule c. 1 cm in diameter, smooth, becoming yellowish brown, falling apart into 3 parts, each part 2-valved and 1-seeded. Seeds ovoid to globose, c. 4 mm long, smooth, pale brown to yellowish brown with darker streaks.

Other botanical information

Spirostachys comprises 2 species and is closely related to Excoecaria. Spirostachys africana closely resembles Excoecaria simii (Kuntze) Pax, which is restricted to South Africa and differs in more sharply toothed leaves without glands at petiole apex.

Spirostachys venenifera

Spirostachys venenifera (Pax) Pax is a shrub or small tree up to 15 m tall, occurring in southern Somalia, Kenya and eastern Tanzania. Its wood is used for construction, door frames, ceiling beams, implements, tool handles and carvings, and also for charcoal production. The wood is yellowish brown to pale brown, with brown markings, medium-weight with a density of about 750 kg/m³ at 12% moisture content, and quite durable. The bark and latex are used as fish poison. Tests in mice showed immunosuppressive activity of bark extracts. Spirostachys venenifera is highly poisonous.

Anatomy

Wood-anatomical description (IAWA hardwood codes):

  • Growth rings: 2: growth ring boundaries indistinct or absent.
  • Vessels: 5: wood diffuse-porous; (10: vessels in radial multiples of 4 or more common); 13: simple perforation plates; 22: intervessel pits alternate; (23: shape of alternate pits polygonal); 26: intervessel pits medium (7–10 μm); 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 41: mean tangential diameter of vessel lumina 50–100 μm; 48: 20–40 vessels per square millimetre; 49: 40–100 vessels per square millimetre; 58: gums and other deposits in heartwood vessels.
  • Tracheids and fibres: (60: vascular/vasicentric tracheids present); 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled.
  • Axial parenchyma: 76: axial parenchyma diffuse; (77: axial parenchyma diffuse-in-aggregates); (86: axial parenchyma in narrow bands or lines up to three cells wide); 92: four (3–4) cells per parenchyma strand; 93: eight (5–8) cells per parenchyma strand.
  • Rays: 96: rays exclusively uniseriate; 104: all ray cells procumbent; (106: body ray cells procumbent with one row of upright and/or square marginal cells); (109: rays with procumbent, square and upright cells mixed throughout the ray); 113: disjunctive ray parenchyma cell walls present; 116: 12 rays per mm.
  • Mineral inclusions: 136: prismatic crystals present; 137: prismatic crystals in upright and/or square ray cells; 138: prismatic crystals in procumbent ray cells.

(P. Mugabi, P.E. Gasson & E.A. Wheeler)

Growth and development

Young trees may have spiny branches. The trees grow very slowly. They are usually deciduous, but sometimes can be nearly evergreen, shedding the old leaves when young leaves develop. In southern Africa, trees usually start to flower in September before new leaves develop, and flowers may be present until January. Fruits ripen 1–2 months after flowering.

Although the tree is poisonous, several animals feed on it; birds such as guinea-fowl, francolin and doves eat the fruits, and large herbivores such as antelopes, elephants and rhinoceros young foliage. Squirrels, often nesting in the hollow bole, feed on the young leaves, bark and seeds.

Ecology

Spirostachys africana occurs in deciduous woodland and wooded grassland, often on termite mounts and stony slopes, sometimes in thickets, up to 1350 m altitude. The largest trees are found near streams and seasonal watercourses. Spirostachys africana prefers well-drained sandy or sandy loam soils. In southern Africa, it is often associated with Colophospermum mopane (Benth.) J.Léonard and Acacia, Brachystegia and Combretum spp.

Propagation and planting

In Botswana fresh seeds showed a germination rate of 55–80% 1–3 weeks after sowing, without pre-treatment. They can be sown in containers filled with river sand, with the seeds pushed into the sand until level. They should be kept moist. Seeds should be selected carefully because they are often infested with moth larvae.

Management

Trees can be coppiced, but the average number of shoots per stump is small (0.4–1).

Diseases and pests

The seeds may be infested with the larvae of a moth (Emporia melanobasis), and these may cause the seed to jump into the air for several centimetres.

Handling after harvest

The boles are often hollow, and larger dimensions of wood are therefore difficult to obtain. Star shakes often develop during log drying. In an inventory in KwaZulu-Natal (South Africa), the mean length of posts used in house building was 2–2.5 m and the mean diameter 7.5–9.5 cm.

Genetic resources

There are no indications that Spirostachys africana is currently threatened; it is both widespread and locally common. However, in many regions its wood is greatly appreciated and sought for, and regulation of the yield is there needed to avoid too much pressure on the populations. A study in 2007 in southern Tanzania showed that the trees were harvested on a large scale below the legally prescribed minimum bole diameter. In South Africa the bark is locally in high demand for medicinal purposes, but it seems to be still readily available.

Prospects

Spirostachys africana produces one of the most beautiful African woods. In addition, it has a nice, long-lasting odour. It is in high demand for high-grade furniture, turnery and fancy articles. The often small size and poor shape of the bole with commonly rotten or hollow heart makes that the timber is often only available in small sizes and limited quantities. Very little research has been done on propagation and possibilities of domestication for this valuable species, which could be worthwhile in spite of its low growth rates.

Major references

  • Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
  • Chikamai, B.N., Githiomi, J.K., Gachathi, F.N. & Njenga, M.G., undated. Commercial timber resources of Kenya. Kenya Forestry Research Institute (KEFRI), Nairobi, Kenya. 164 pp.
  • Coates Palgrave, K., 2002. Trees of southern Africa. 3rd Edition. Struik Publishers, Cape Town, South Africa. 1212 pp.
  • Grace, O.M., Prendergast, H.D.V., Jäger, A.K. & van Staden, J., 2002. Bark medicines in traditional healthcare in KwaZulu-Natal, South Africa: an inventory. South African Journal of Botany 69(3): 301–363.
  • Neuwinger, H.D., 1996. African ethnobotany: poisons and drugs. Chapman & Hall, London, United Kingdom. 941 pp.
  • Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
  • Palmer, E. & Pitman, N., 1972–1974. Trees of southern Africa, covering all known indigenous species in the Republic of South Africa, South-West Africa, Botswana, Lesotho and Swaziland. 3 volumes. Balkema, Cape Town, South Africa. 2235 pp.
  • Radcliffe-Smith, A., 1996. Euphorbiaceae, subfamilies Phyllantoideae, Oldfieldioideae, Acalyphoideae, Crotonoideae and Euphorbioideae, tribe Hippomaneae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 9, part 4. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 1–337.
  • Tietema, T., Merkesdal, E. & Schroten, J., 1992. Seed germination of indigenous trees in Botswana. African Centre for Technology Studies, Nairobi, Kenya. 106 pp.
  • van Wyk, B.E., van Heerden, F. & van Oudtshoorn, B., 2002. Poisonous plants of South Africa. Briza Publications, Pretoria, South Africa. 288 pp.

Other references

  • Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
  • Bryce, J.M., 1967. The commercial timbers of Tanzania. Tanzania Forest Division, Utilisation Section, Moshi, Tanzania. 139 pp.
  • Dale, I.R. & Greenway, P.J., 1961. Kenya trees and shrubs. Buchanan’s Kenya Estates Limited, Nairobi, Kenya. 654 pp.
  • Duri, Z.J., Hughes, N.A. & Munkombwe, N.M., 1992. Diterpenoids from Spirostachys africana. Phytochemistry 31(2): 699–702.
  • Gaugris, J.Y., van Rooyen, M.W., Bothma, J. du P. & van der Linde, M.J., 2007. Hard wood utilization in buildings of rural households of the Manquakulane community, Maputaland, South Africa. Ethnobotany Research & Applications 5: 97–114.
  • Gelfand, M., Mavi, S., Drummond, R.B. & Ndemera, B., 1985. The traditional medical practitioner in Zimbabwe: his principles of practice and pharmacopoeia. Mambo Press, Gweru, Zimbabwe. 411 pp.
  • Gilbert, M.G., Holmes, S. & Thulin, M., 1993. Euphorbiaceae. In: Thulin, M. (Editor). Flora of Somalia. Volume 1. Pteridophyta; Gymnospermae; Angiospermae (Annonaceae-Fabaceae). Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 267–339.
  • Govaerts, R., Frodin, D.G. & Radcliffe-Smith, A., 2000. World checklist and bibliography of Euphorbiaceae (with Pandaceae). Royal Botanic Gardens, Kew, Richmond, United Kingdom. 1620 pp.
  • Luoga, E.J., Witkowski, E.T.F. & Balkwill, K., 2004. Regeneration by coppicing (resprouting) of miombo (African savanna) trees in relation to land use. Forest Ecology and Management 189: 23–35.
  • Mathabe, M.C., Nikolova, R.V., Lall, N. & Nyazema, N.Z., 2006. Antibacterial activities of medicinal plants used for the treatment of diarrhoea in Limpopo Province, South Africa. Journal of Ethnopharmacology 105(1–2): 286–293.
  • Mathabe, M.C., Hussein, A., Nikolova, R.V., Basson, A., Meyer, J.J.M. & Lall, N., 2008. Antibacterial activities and cytotoxicity of terpenoids isolated from Spirostachys africana. Journal of Ethnopharmacology 116(1): 194–197.
  • Maundu, P. & Tengnäs, B. (Editors), 2005. Useful trees and shrubs for Kenya. World Agroforestry Centre - East and Central Africa Regional Programme (ICRAF-ECA), Technical Handbook 35, Nairobi, Kenya. 484 pp.
  • Ngobeni, H.D. & Mashela, P.W., 2005. Effect of Spirostachys africana on cowpea weevil during seed storage. In: Tenywa, J.A., Adipala, E., Nampala, P., Tusiime, G., Okori & Kyamuhangire, W. (Editors). African Crop Science Conference Proceedings, 5–9 December 2005, Kampala, Uganda, 7(1): 377–380.
  • Njiro, S.M., Nyaga, P.N. & Kofi Tsekpo, 1994. Immunosuppressive effect of Spirostachys venenifera Pax in mice. Bulletin of Animal Health and Production in Africa 42(1): 47–50.
  • Nube, T.G., 2003. Sistema de comercialização de Spirostachys africana (sandal) para os artesãos da Cidade de Maputo. Bachelor’s thesis, Department of Forestry Engineering, Faculty of Agronomy and Forestry Engineering, UEM, Maputo, Mozambique. 40 pp.
  • Radcliffe-Smith, A., 1987. Euphorbiaceae (part 1). In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 407 pp.
  • Radcliffe-Smith, A., 2001. Genera Euphorbiacearum. Royal Botanic Gardens, Kew, United Kingdom. 455 pp.
  • Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
  • van Wyk, B.E. & Gericke, N., 2000. People’s plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 pp.
  • Wimbush, S.H., 1957. Catalogue of Kenya timbers. 2nd reprint. Government Printer, Nairobi, Kenya. 74 pp.

Sources of illustration

  • Coates Palgrave, K., 2002. Trees of southern Africa. 3rd Edition. Struik Publishers, Cape Town, South Africa. 1212 pp.
  • Palmer, E. & Pitman, N., 1972–1974. Trees of southern Africa, covering all known indigenous species in the Republic of South Africa, South-West Africa, Botswana, Lesotho and Swaziland. 3 volumes. Balkema, Cape Town, South Africa. 2235 pp.
  • Radcliffe-Smith, A., 1996. Euphorbiaceae, subfamilies Phyllantoideae, Oldfieldioideae, Acalyphoideae, Crotonoideae and Euphorbioideae, tribe Hippomaneae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 9, part 4. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 1–337.

Author(s)

  • I. Kopong, Department of Crop Science and Production, Botswana College of Agriculture, Private Bag 0027, Gaborone, Botswana
  • W. Mojeremane, Department of Crop Science and Production, Botswana College of Agriculture, Private Bag 0027, Gaborone, Botswana

Correct citation of this article

Kopong, I. & Mojeremane, W., 2012. Spirostachys africana Sond. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 11 July 2021.